(757a) Tar Reforming Catalyst Development and Scale up for Use In a Biomass Gasification Pilot Plant

At the National Renewable Energy Laboratory (NREL) an indirect gasification pilot plant is used to study biomass conversion to syngas. Tars contained in the raw syngas are subsequently removed via steam reforming in a fluidized bed, full stream reformer (FSR). Fluidizable catalysts developed for use in the FSR are first screened for reforming performance with a fixed-bed, bench scale micro-activity test system (MATS). The primary goal of this study was to screen catalysts of varied composition in the MATS reactor and identify the best performing catalysts for scale up and use in the pilot plant FSR for syngas cleanup. The second goal of this study was to determine the efficacy of anti-coking additives such as magnesium oxide (MgO), potassium oxide (K2O), and tin (Sn) on catalyst activity. The initial experimental regime consisted of ethylene steam reforming with a steam to carbon ratio of ~4.9 and a gas hourly space velocity (GHSV) of ~68,000 in a 0.5 inch diameter quartz tube reactor. After initial screening, the catalysts that performed best were next evaluated at double the space velocity in order to identify more subtle differences in reforming activity. Two NREL catalysts were chosen for scale up and testing in the FSR. Those catalysts were further validated in the MATS system using a model syngas feed with 20 ppm sulfur, a composition that is representative of raw syngas produced in the gasifier. Both bench and pilot scale reforming results obtained with these catalysts will be discussed.